ALL THE ACTION AT AIPADby Rachel CorbettThe first thing you see when you walk through the doors of the Park Avenue Armory for the annual Association of International Photography Art Dealers photo show (AIPAD), Mar. 29-Apr. 1, 2012, is a cluster of bare, muscular male chests on the wall at the Yossi Milo Gallery booth. The intimate photographs of young American soldiers in Liberia and Afghanistan, taken by the late war correspondent Tim Hetherington three years before his death in 2011 while working in Libya, make for a forceful point of entry, but set a martial tone that does not carry through the rest of the fair.